# Water on Mars - what happened to it? **URL:** \ **Category:** Factual Questions\ **Created:** [December 7, 2000, 1:42pm UTC](https://boards.straightdope.com/t/water-on-mars-what-happened-to-it/44468 "2000-12-07T13:42:20Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [December 7, 2000, 1:42pm UTC](https://boards.straightdope.com/t/water-on-mars-what-happened-to-it/44468/1 "2000-12-07T13:42:20Z")
The physical evidence seems pretty compelling that Mars once had torrents of water over much of its surface. Not only does it have features that look like they must have been river valleys, but there’s new evidence of sedimentary geological (Areological? Help me) structures. It also looks pretty likely that the polar caps are made of ice, but they look pretty small compared to the amount of water that must have been there. If the stuff just evaporated, it would still be in the atmosphere, but there isn’t much of THAT either. The surface is largely red, so maybe much of it went to forming oxides. So, what happened to all the water? Do the amounts add up? ---
**Author:** ![Phobos](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@Phobos](https://boards.straightdope.com/u/Phobos)\ **Post date:** [December 7, 2000, 1:47pm UTC](https://boards.straightdope.com/t/water-on-mars-what-happened-to-it/44468/2 "2000-12-07T13:47:42Z")
Aside from the ice caps (which, BTW, are mostly frozen carbon dioxide…dry ice), the next best location would be underground (frozen aquifers). This is still to be confirmed though. ---
**Author:** ![Phobos](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@Phobos](https://boards.straightdope.com/u/Phobos)\ **Post date:** [December 7, 2000, 1:50pm UTC](https://boards.straightdope.com/t/water-on-mars-what-happened-to-it/44468/3 "2000-12-07T13:50:48Z")
Also a quote from this website… [http://itss.raytheon.com/cafe/qadir/q1444.html](http://itss.raytheon.com/cafe/qadir/q1444.html) > [@](#): > > Where did all the martian water go? Mars may have lost to space a substantial amount of its atmosphere, including carbon dioxide, nitrogen, and water vapor. The loss of carbon dioxide – a potent greenhouse gas – would have caused Mars to become much colder and drier. While some of the water may have been irretrievably lost to space, most of it may still reside in various reservoirs on Mars. Among these are a permafrost layer up to 1 km thick, clay minerals and oxidation products, and layered deposits at the poles. Taken together, these reservoirs could hold the equivalent of a layer of water around 0.5 km thick, if spread uniformly over the martian surface. ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [December 7, 2000, 1:54pm UTC](https://boards.straightdope.com/t/water-on-mars-what-happened-to-it/44468/4 "2000-12-07T13:54:29Z")
An amount which pales, of course, in comparison to the water that, if totally released from all locations, would cover the surface area of the Earth. 🙂 ---
**Author:** ![Fiver](https://avatars.discourse-cdn.com/v4/letter/f/e274bd/32.png) [@Fiver](https://boards.straightdope.com/u/Fiver)\ **Post date:** [December 7, 2000, 1:57pm UTC](https://boards.straightdope.com/t/water-on-mars-what-happened-to-it/44468/5 "2000-12-07T13:57:21Z")
Some of it is probably in deep aquifers. Much of it is in the northern ice cap, which is much larger than it appears; besides the visible white part, there’s a larger mass of ice which is under the top layer of regolith surrounding the white part. A very large portion of the “missing water” is bound up in permafrost all over the planet. The best evidence for this is the “splosh” craters seen in many places. These are impact craters like any other, except the ejecta surrounding the crater is rounded and resembles paint or mud spatters. This suggests that the impactor hit permafrost, and then the heat of the impact turned it into mud which “sploshed” onto the ground around it. But to be perfectly frank, we currently just don’t know exactly what happened to Mars’s water. That’s one of the reasons we need to go there.